1. Field of the Invention
The present invention relates to an apparatus with an easily cleaned, surface coating, which is heat-resistant at least up to 300° C.
2. Description of the Related Art
Equipping objects with dirt-repellant substances is generally known. For example, it is also known to treat glass, glass ceramic, glazed, enamel or even stone surfaces with silicones in order to make these surfaces dirt and water-repellant. Similarly metal and plastic surfaces can be made dirt and water-repellant. For that purpose usually the surfaces of the objects to be treated are made hydrophobic by application of a liquid composition. Many different chemicals, especially silicone oils and/or fluorinated silanes, are used for this purpose. The surfaces treated in this manner have proven to be difficult to wet, whereby water forms beads on them. Dirt adheres only weakly on the treated surfaces and may be easily removed.
The above procedure has however the disadvantage that the applied chemicals only react directly with the OH groups immediately available on the substrate material and only form strong bonds there. Also a suitable pre-treatment, for example with a hydrogen/oxygen plasma or a suitable adhesive substance, can only increase the density of the applied chemicals on the surface of the article, especially a glass, metal and plastic article. However this type of pre-treatment cannot increase the thickness of the coating or layer, so that only monomolecular hydrophobic layers are produced, which are quickly rubbed off during usage, especially under mechanical loads or stresses, such as occur during cleaning with household auxiliary and cleaning agents. Thus the desired property of easy cleanability is lost.
It has thus already been attempted to increase the adherence or service life of this sort of coating. For example, EP A 0,658,525 describes the manufacture of a water-repellant multi-layer film. For this purpose three different sol-solutions are made, mixed and applied to a glass substrate and gel coatings are produced on glass surfaces. A metal oxide surface coating is then produced by heating. A fluoroalkylsilane layer is then applied on this metal oxide coating.
JP A 11 092 175 describes a process, in which methoxysilane or an ethoxysilane compound, which contains a fluorocarbon chain, is fixed on the surface of small particles with diameters of 100 nm. Then the modified particles are dissolved in an aqueous medium and applied to a surface to be coated, the solvent is removed and the residue is subsequently burned into the surface. In this way a surface coated with small hydrophobic particles is produced.
A method of making a water-repellant surface is described in WO 99/64363, in which the surface of the glass is first roughened and the metal ions present on the surface are removed. After that a water-repellant film is applied to the surface to be treated in a known manner. By roughening the surface the indentations of the roughened surface are filled with hydrophobic material.
In WO 99/02463 a method of making a scratch resistant coating is described, in which an organic substance with a silicone-type network is applied to the surface. Subsequently a heat treatment is performed. The temperature and duration of the heat treatment are selected so that the purely organic layer is largely destroyed and/or removed. However the inorganic molecules in the upper-most layer of the substrate and the organic molecules of the applied coating can bond chemically. In this way an organic substance, for example a methyl group, is bonded directly to the silicon atom of the glass surface directly with a Si—C bond.
DE 695 02671 T2 (WO9S/24053) describes a signaling device with a display screen. The display screen has a non-absorbing coating layer made from a hybrid inorganic-organic material and an inorganic network of silicon oxide and metal oxide. In that the polymer chains are interwoven with the inorganic network and form a hybrid inorganic-organic network. However it has been shown that the organic components, especially hydrophobic organic components, such as fluoroalkyls, are not built into this sort of coating or layer uniformly, but that they are deposited substantially on the surface facing the substrate layer. For this reason this outer hydrophobic coating is comparatively easily rubbed off or removed by rubbing.
All the coatings made with these prior art methods have hydrophobic and, if necessary, dirt-repellant properties, which have proven to be not sufficiently permanent and are rapidly lost, especially, under application of mechanical stress.